As the number of potent drugs in clinical use increases, untoward side effects become more numerous. Because of its central position in metabolism, the liver is the target of many side reactions to drugs, which vary from a mere temporary nuisance to rapidly fatal hepatic insufficiency. The possibility of drug-induced hepatic injury has impeded the further development of many drugs or discouraged their clinical application, and sometimes has led to their withdrawal even after widespread clinical use. Some hepatic reactions to drugs are predictable, as, for instance, those resulting from overdosage of potent remedies. Other drug reactions are unpredictable, occurring only in a few patients and without clear relationship to the dosage.

Classification of drug-induced hepatic injury is important, since the problems of drug administration have now become worldwide. One basis for this classification is functional defect.1 Some investigators, however, have used as a guide the histologic manifestations of